Stochastic and Relaxation Processes in Argon by Measurements of Dynamic Breakdown Voltages

Statistically based measurements of breakdown voltages U _b and breakdown delay times td and their variations in transient regimes of establishment and relaxation of discharges are a convenient method to study stochastic processes of electrical breakdown of gases, as well as relaxation kinetics in afterglow. In this paper the measurements and statistical analysis of the dynamic breakdown voltages U _b for linearly rising (ramp) pulses in argon at 1.33 mbar and the rates of voltage rise k up to 800 V s ^–1 are presented. It was found that electrical breakdowns by linearly rising (ramp) pulses is an inhomogeneous Poisson process caused by primary and secondary ionization coefficients α , γ and electron yield Y variations on the voltage (time). The experimental breakdown voltage distributions were fitted by theoretical distributions by applying approximate analytical and numerical models. The afterglow kinetics in argon was studied based on the dependence of the initial electron yield on the relaxation time Y ₀ (τ ) derived from fitting of distributions. The space charge decay was explained by the surface recombination of nitrogen atoms present as impurities. The afterglow kinetics and the surface recombination coefficients on the gas tube and cathode were determined from a gas‐phase model. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)